A parked truck with no driver at the wheel rolled down a hill and crashed through a Long Island drycleaners Tuesday — sending glass, bricks and an awning flying as people scrambled for their lives.

“I was inside [the store] and saw something strange. The truck was going diagonal, towards the store,” said John Chung, owner of Harbour Hills Drycleaning in Roslyn. “There was no one inside the truck.”

Moments later, there was a “big bang,” said Christopher Cuartas, was working next door at a cellphone shop.

Cuartas said he next “heard a lot of glass breaking and another big bang” — and then he ran to the scene, where he soon dragged an injured and terrified seamstress from the back of the drycleaners.

“The awning came down with bricks,” Cuartas added in an interview Tuesday. “I saw a lot of dust.”

Driver Maurico Munez from Green Mansions Tree Company told The Post he parked atop a small hill, pulled the parking brake and ran to grab lunch.

“I was out of the truck for ten minutes,” he said. “I came back and my truck was gone. … I was so scared when I saw it.”

The Nassau county police said no charges had been immediately brought, but the investigation is ongoing.

Chung said he watched in terror while the truck rolled right at him and his storefront. He got out, but the seamstress was not as lucky.

“She was crunching down,” he said. “She was scratched, and [there was] blood.”

Cuartas soon pulled the seamstress to safety and she was treated at a nearby hospital.